Nonlinear Gravitational Recoil from the Mergers of Precessing Black-Hole Binaries

Understand

We present results from an extensive study of 88 precessing, equal-mass black-hole binaries with large spins (83 with intrinsic spins of 0.8 and 5 with intrinsic spins of 0.9)and use these data to model new nonlinear contributions to the gravitational recoil imparted to the merged black hole.

• We find a new effect, the cross kick, that enhances the recoil for partially aligned binaries beyond the hangup kick effect.
• This has the consequence of increasing the probabilities of recoils larger than 2000 km/s by nearly a factor two, and, consequently, of black holes getting ejected from galaxies, as well as the observation of large differential redshifts/blueshifts in the cores of recently merged galaxies.